RFR (XS): 8185102: TestSAServer.java fails due to "sun.jvm.hotspot.types.WrongTypeException: field "_stack_traversal_mark"

[Roman Kennke]

This is a followup to 8180932: Parallelize safepoint cleanup.

TestSAServer.java fails because nmethod::_stack_traversal_mark is now
jlong instead of the previous int.

http://cr.openjdk.java.net/~rkennke/8185102/webrev.00/
<http://cr.openjdk.java.net/%7Erkennke/8185102/webrev.00/>

I verified that the failing test passes now.

Roman